I sometimes get questions about how to paint vehicles so I thought I would put together a short tutorial using some 1/72-scale WW2 tanks. I use two different approaches to painting vehicles. This post addresses using washes over a white primer. The other approach uses a black primer and full strength paints.
Washes are basically translucent layers of paint that trap some wavelengths of light and allow others wavelengths (corresponding to the colour you "see") to bounce off the object. The white undercoat and translucent paint are one way to create the colour shift that makes miniatures look realistic (see below).
Prep and Priming: You can figure out how to build you own model. Once built, I prime with a can of cheap flat white spray paint. This gives the washes something to grip onto. Here you can see a 1/76-scale Matchbox set: a Char B and an FT-17.
Base-colour wash: The base colour of the model is fairly straight forward. I mix the paint colour I want with some Future floor wax (now sold as Pledge Klear with Future). The ratio is about 50-50. You can then adjust that ratio to get the effect you want and apply it to your model. I've shown a model in progress below. The paint I used was Vallejo's British Uniform brown (which dilutes to a nice tan).
One of the tricks to "realistic" looking models is accounting for the colour shift. Basically, when you see a model, your mind "thinks" it is looking at the the object that is far away. To make the vehicle look realistic, you must lighten the colour enough that it corresponds with the natural lightening of distant objects due to refraction of light in the atmosphere. Using a translucent wash helps create this colour shift and the result you want is a colour that allows some of the white undercoat to almost show through on the raised parts of the model.
Detailing: Once you have the base colour down and dry (above) you can then apply additional paint (below) to detail the model. On the Char B, I have washed on a second (green) colour (Vallejo German Uniform Green, I think) and also rusted the treads and some bolts. I left the FT-17 plain, but added the rust effect.
Magic dip: The final step is to add in some shadows using the magic dip. The magic dip is a wash comprising 1 part black/brown paint mixed with about 20 parts Future. I keep a separate pot of dip mixed up so I don't have to make it each time. The dip will also ruin your brushes so use an old brush to apply it. Painting this wash over the figure darkens the model and the colour runs into the recesses to create shadows. The result is dramatic.
You can get a decent effect using this technique over a single-coloured base coat. Where this technique really shines is multi-coloured camo. You can see the Char B (above) really pop with the wash. You get a nice muted camo which looks kind of dirty.
The raised areas of the tank (which would get rubbed a lot in daily use) have a worn look to them--like the metal is about to wear through the paint. This most evident on the top edge of the turret wall. The dip runs into the crevasses and creates a nice shadow. This is most evident in the panels on the side of the tank.
Once this dries, you can decal, seal and dull coat and/or drybrush on some dust. With the Char B, the 20-year-old decals all shattered as soon as I put them in the water (arrrgh) so I may have to go buy some and come back to the tank later on.
An important consideration in choosing you base colour is that you can add darker washes over lighter ones, but not the other way around! If you are going to do a two-tone wash, use the lighter colour as the base colour. Above I did a two-tone scheme on an Airfix Matilda II, with the base being the light green. The decals really help pop an otherwise drab scheme.
The beauty of this technique is its speed and simplicity. Excluding drying time, this takes about 5-10 minutes per tank if you work in a batch of 3-6 and it doesn't require a lot of careful brushwork or judgment.